Object provided with an electro-optic display device

ABSTRACT

An object includes an electro-optic display device provided with an optically active element, the optical properties thereof can be modified by applying an electric voltage or current between at least one electrode and one corresponding auxiliary electrode, between which the optically active element is disposed. The object further includes a middle part which delimits an opening closed by a crystal including a bottom surface beneath which the electro-optic display device is arranged. The crystal is provided with an opaque frame which is made remotely from the edges of the opening and which covers the contour of the electro-optic display device so as to conceal electrical connection elements. The electro-optic display device defines an active display area which is confined by the opaque frame, such that, when the electro-optic display device is activated and displaying information, a transparent area remains between the opaque frame and the edges of the opening.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/597,223, filed Oct. 9, 2019, which claims priority to European PatentApplication No. 18204699.5 filed on Nov. 6, 2018, the entire disclosuresof each of which are hereby incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an object provided with anelectro-optic display. More specifically, the invention relates to anobject such as a timepiece or a smartphone comprising a frame delimitingan opening closed by a crystal beneath a bottom surface of which anelectro-optic display device is arranged.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

The present invention relates to the field of electro-optic displaydevices. The term “electro-optic display device” is understood to mean adisplay device comprising an optically active element whose opticalproperties can be modified by applying an electric current or voltage.The display devices that comply with this definition in particularinclude liquid crystal display devices (also known as LCD devices),organic light emitting diode devices (also known as OLED devices),electrochromic display devices and electrophoretic display devices.

The electro-optic display devices concerned by the present inventionconventionally comprise at least one substrate which acts as a supportfor an optically active element disposed between at least one electrodeand one corresponding auxiliary electrode, and whose optical propertiescan be modified by applying an electric current or voltage between theseat least one electrode and auxiliary electrode.

For the purposes of illustration only, the case of a liquid crystaldisplay device can be considered, for example of the twisted nematic(TN) type comprising a front substrate which extends parallel to andremotely from a rear substrate. These front and rear substrates arejoined to one another by means of a sealing frame which delimits asealed enclosure confining the liquid crystal. Electrodes and auxiliaryelectrodes are structured on the faces facing each other of the frontand rear substrates.

The application of an electric voltage between a determined electrodeand a determined auxiliary electrode makes it possible to modify theoptical properties of the liquid crystal at the crossing point betweenthis electrode and this auxiliary electrode.

In order to ensure correct operation of a liquid crystal display device,the electrodes and auxiliary electrodes thereof must be connected to anelectronic power and control device at least partially locatedexternally to the display device. For this purpose, one of the twosubstrates, usually the rear substrate, is provided such that it islarger than the front substrate and this additional surface is used toextend, via electrically-conductive tracks, the auxiliary electrodessupported by the rear substrate outside of the sealing frame of thedisplay device. Similarly, the electrodes supported by the frontsubstrate are transferred to the rear substrate, for example by means ofelectricity-conducting balls dispersed in the sealing frame. Theseelectrically-conductive balls are in contact, on the one hand with theelectrodes, and on the other hand with conductive tracks which run alongthe rear substrate and allow these electrodes to be extended outside ofthe sealed enclosure delimited by said sealing frame. Thanks toelectrical connectors, the conductive tracks, and thus the electrodesand auxiliary electrodes of the liquid crystal display device can beconnected to the external electronic power and control device.

Numerous applications exist today wherein an electro-optic displaydevice such as a liquid crystal display device of the type describedbriefly hereinabove is sought to be attached. Among the examples thatimmediately come to mind are timepieces such as wristwatches orsmartphones. Such portable objects comprise a frame (also referred to asa “middle part” in the specific case of wristwatches) which delimits anopening that is closed by a crystal. This crystal comprises a topsurface directed towards an observer and a bottom surface, opposite thetop surface, and to which a liquid crystal display device, for example,is rigidly connected. This liquid crystal display device is intended todisplay information that will be discernible to the user through theopening delimited by the frame of the portable object.

The problem faced by all designers looking to equip an object, such as awristwatch or smartphone, with an electro-optic display device directlyattached to the bottom surface of the crystal, lies in the need, forunderstandable aesthetic reasons, to conceal from the user's view all ofthe electrical connection elements that are required to connect theelectro-optic display device to the external electronic power andcontrol device thereof.

The most common solution to date for overcoming this problem consists ingiving the front substrate via which the electro-optic display device isrigidly connected to the bottom surface of the crystal a dimension thatis equal to or substantially the same as that of this crystal, and inproviding a rear substrate of a larger dimension than the frontsubstrate in order to obtain a large enough surface area for arrangingall of the elements required for the electrical connection of theelectro-optic display device to the external electronic power andcontrol device thereof. The portion of the rear substrate that exceedsthe dimensions of the crystal extends beneath the frame which is, bydefinition, opaque, of the portable object and is thus hidden from theuser's view.

In these embodiments of the prior art, the active area of theelectro-optic display device, i.e. the scope over which such anelectro-optic display device can display information, is substantiallyequal to the scope of the opening delimited by the frame of the object.Objects such as a wristwatch comprising two superimposed display devicesof the electro-optic type are already known. More specifically, theupper electro-optic display device is arranged such that, when notdisplaying information, it is semi-transparent and allows informationdisplayed by the lower electro-optic display device to be viewed.However, this solution appears less suited to the case where the lowerdisplay device is not an electro-optic display device. Such is the case,for example, if an object such as a wristwatch is equipped, for example,with a dial above which indicator hands move. More specifically, sincethe electro-optic display device that is arranged above the hand displaydevice is disposed between two polarisers, less than 50% of the externallight that falls on this electro-optic display device will penetrate theinside of the watch case, such that the dial and the hands movingthereabove will appear dark and difficult to perceive by the user. Thereis thus a need in the prior art for an object, in particular a portableobject such as a wristwatch or a smartphone, comprising a frame thatdelimits an opening through which can be viewed not only the informationdisplayed by the electro-optic display device, but also the informationdisplayed by a second display device arranged beneath the electro-opticdisplay device, while hiding from the user's view the constructionelements and electrical connection elements, whose view thereof would beaesthetically detrimental for the object.

SUMMARY OF THE INVENTION

The purpose of the present invention is thus to fulfil theaforementioned and other needs by providing an object, in particular aportable object such as a timepiece or a smartphone, provided with afirst electro-optic display device and a second display device arrangedbeneath the electro-optic display device, the information displayedrespectively by the first electro-optic display device and by the seconddisplay device being discernible through the opening delimited by theframe of the object. It goes without saying that all of the elementsrequired for the electrical connection of the first electro-opticdisplay device to the external electronic power and control devicethereof must remain indiscernible to the user.

For this purpose, the present invention relates to an object, inparticular a portable object such as a timepiece or smartphone, thisobject comprising an electro-optic display device externally delimitedby a contour and which is provided with an optically active element,whose optical properties can be modified by applying an electric voltageor current between at least one electrode and one correspondingauxiliary electrode, between which the optically active element isdisposed, the object further comprising a frame which delimits anopening closed by a crystal, the crystal comprising a top surface and abottom surface beneath which the electro-optic display device isarranged, the object further comprising an external electronic power andcontrol device in addition to elements for the electrical connection ofthe electro-optic display device to the external electronic power andcontrol device, the crystal being provided with an opaque frame which ismade remotely from the edges of the opening and which covers the contourof the electro-optic display device so as to conceal the electricalconnection elements, the electro-optic display device defining an activedisplay area which is circumscribed by the opaque frame, such that, evenwhen the electro-optic display device is activated and displaysinformation, a transparent area remains between the opaque frame and theedges of the opening.

According to one specific embodiment of the invention, the objectcomprises a second device for displaying information arranged beneaththe electro-optic display device and at least partially visible throughthe transparent area.

Thanks to these features, the present invention provides an object, inparticular a portable object such as a wristwatch or a smartphone,provided with an electro-optic display device, an active display area ofwhich, defined by an optically active element whose optical propertiescan be modified by applying an electric voltage or current, is delimitedby an opaque frame which conceals the electrical connection elements ofthe electro-optic display device. As a result, even when the activedisplay area is displaying information, a transparent area devoid of anydisplayed information remains between the opaque frame and the edge ofthe opening delimited by the middle part of the object, whichtransparent area can be used to make visible, for example, a seconddisplay device disposed beneath the electro-optic display device.

One example illustrating the possibilities procured by the presentinvention is that of a wristwatch equipped with an electro-optic displaydevice according to the present invention and further comprising a dialprovided with hands arranged beneath the electro-optic display device.Thanks to the features of the invention, the user of the wristwatch thussimultaneously views through the crystal of his/her watch the digitalinformation displayed by the active area of the electro-optic displaydevice, and the analogue information displayed by the hands that moveover the dial. Thanks to the invention, a hybrid watch is thus obtained,provided with a “screen”-type display and an analogue display of the“hand” type, the appearance thereof being original and innovative.However, it should be noted that the present invention is not limited tothe use of an analogue display device disposed beneath the electro-opticdisplay device, and that a first and a second electro-optic displaydevice can very well be combined with one another, the secondelectro-optic display device thus being adapted such that it displaysinformation in the transparent area located between the edge of themiddle part and the opaque frame. There is thus the possibility ofchoosing to activate only the first electro-optic display deviceattached beneath the crystal, or only the second electro-optic displaydevice disposed beneath the first, or to activate the first and secondelectro-optic display devices simultaneously.

BRIEF DESCRIPTION OF THE FIGURES

Other characteristics and advantages of this invention will be betterunderstood upon reading the following detailed description of oneexample embodiment of a portable object of the wristwatch type accordingto the invention, said example being provided for the purposes ofillustration only and not intended to limit the scope of the invention,given with reference to the accompanying drawing, wherein:

FIG. 1 is a partial sectional view of a first embodiment of a watch caseaccording to the invention, a middle part thereof delimiting an openingclosed by a crystal to the bottom surface of which an electro-opticdisplay device of the liquid crystal display device type is rigidlyconnected, a second display device comprising a first pipe supporting afirst hand and a second pipe arranged concentrically inside the firstpipe and supporting a second hand being disposed beneath theelectro-optic display device, this electro-optic display device beingconnected to an external electronic power and control device via aflexible printed circuit (or FPC), which is passed in a hollow tubearranged inside the second pipe;

FIG. 2 is a partial sectional view of a second embodiment of a watchcase according to the invention, wherein the electro-optic displaydevice is connected by means of a first and of a second flexible printedcircuit to the external electronic power and control device thereofarranged beneath the second display device via a transparent printedcircuit board arranged beneath the electro-optic display device, thesecond display device being arranged beneath the transparent printedcircuit board;

FIG. 3 is a partial sectional view of a third embodiment of a watch caseaccording to the invention, wherein transparent conductive tracks arestructured on the bottom surface of the crystal, the electro-opticdisplay device being connected to these transparent conductive tracks bymeans of a first flexible printed circuit, the transparent conductivetracks being themselves connected by means of a second flexible printedcircuit to the external electronic power and control device of theelectro-optic display device, a second display device being disposedbeneath the electro-optic display device;

FIG. 4 is a partial sectional view of a fourth embodiment of a watchcase according to the invention, which differs from the embodiment shownin FIG. 3 only in that the first flexible printed circuit is dividedinto two parts connected to one another by means of an electricalconnector in order to facilitate assembly;

FIG. 5 is a partial sectional view of a fifth embodiment of a watch caseaccording to the invention, wherein a flexible connector formed by analternation of electrically-conductive sheets and of insulatingelastomer sheets allows an electro-optic display device to be connectedto transparent conductive tracks structured on the bottom surface of thecrystal, a flexible printed circuit allowing the transparent conductivetracks to be connected to an external power and control device of theelectro-optic display device, a second display device being disposedbeneath the electro-optic display device;

FIG. 6 is a partial sectional view of a sixth embodiment of a watch caseaccording to the invention, wherein the electro-optic display device isattached via the front substrate thereof to the bottom surface of thecrystal and is connected by a wire-based connection method totransparent conductive tracks structured on the bottom surface of thecrystal, a flexible printed circuit allowing the transparent conductivetracks to be connected to the external power and control device of theelectro-optic display device, a second display device being disposedbeneath the electro-optic display device; and

FIG. 7 is a view similar to that of FIG. 6, wherein the electro-opticdisplay device is of the OLED type.

DETAILED DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION

The present invention was drawn from the general inventive ideaconsisting of disposing an electro-optic display device beneath thebottom surface of a crystal sealing an opening delimited by a middlepart of an object, in particular a portable object such as a wristwatchor a smartphone.

The originality of the object according to the invention lies in thefact that the crystal is intended to be provided with an opaque framewhich extends remotely from the edges of the opening delimited by themiddle part and which covers the electro-optic display device at theperiphery thereof, so as to conceal the elements required toelectrically connect the electro-optic display device to the externalelectronic power and control device thereof. Since the active displayarea of the electro-optic display device is circumscribed by the opaqueframe, a transparent area devoid of any displayed information remainsbetween the opaque frame and the edge of the opening delimited by themiddle part of the object. As a result, even when the electro-opticdisplay device is activated and is displaying information, a transparentarea devoid of any displayed information remains between the activedisplay area thereof and the edges of the middle part of the object,through which transparent area, for example, a second device fordisplaying information can be viewed, arranged beneath the electro-opticdisplay device. This second device for displaying information can be ofany kind: it can simply be a decorative pattern; it can also be a secondelectro-optic display device. According to a special embodiment of theinvention, the second display device is a dial above which hands move.Thanks to the invention, a hybrid watch is thus obtained, provided witha “screen”-type display and an analogue display, the appearance thereofbeing original and innovative.

The present invention will now be described with reference to a portableobject of the wristwatch type equipped with an electro-optic displaydevice of the liquid crystal display device type. It goes without sayingthat this example is provided for illustrative, non-limiting purposesonly and that the object can be something other than a timepiece.Broadly speaking, it concerns any type of object, such as a telephone orlaptop comprising a middle part that delimits an opening closed by acrystal through which information displayed by the electro-optic displaydevice is discernible.

Similarly, the choice of electro-optic display device is not limited toliquid crystal display devices and in particular extends to displaydevices of the organic light emitting diode type, as well as toelectrophoretic display devices and to electrochromic display devices.More specifically, these different types of electro-optic displaydevices all comprise at least one substrate which acts as a support foran optically active element (for example twisted nematic orsuper-twisted nematic or vertical alignment liquid crystal for a liquidcrystal display device, active hole-injection, hole-transport andelectron-transport layers for an organic light emitting diode displaydevice, black and white particles or colour particles dispersed in afluid in the case of electrophoretic display devices, liquid or solidelectrolyte in the case of electrochromic display devices), and sets ofelectrodes and auxiliary electrodes used to modify the opticalproperties of the optically active element by applying an electriccurrent or voltage.

It should be noted that, as per the present invention, the term “activedisplay area of an electro-optic display device” is understood to meanthe useful portion of the front surface of the electro-optic displaydevice on which information elements can be displayed. By way ofexample, in the case of an electro-optic display device of the twistednematic liquid crystal type, two front and rear substrates are present,which extend parallel to and remotely from one another, and which arejoined to one another by a sealing frame which delimits a sealedenclosure for confining the liquid crystal. A front polariser film isattached to the top of the front substrate and the polarisationdirection thereof forms a 90° angle with the polarisation direction of arear polariser film attached to the bottom of the rear substrate.

In such a case, the polarisers are referred to as crossed. In this case,the information displayed by the electro-optic display device in theactive display area thereof will appear dark against a transparentbackground. For the active display area to appear opaque, the rearpolariser film can be combined with a reflector or an opaquebacklighting device can be provided beneath the rear substrate. Insteadof the backlighting device, an opaque film can also be used.

The polarisers can also be parallel, i.e. the polarisation directionsthereof can be parallel to one another. Yet another embodiment consistsof combining a circular polariser attached to the top of the frontsubstrate with a metal reflector arranged inside the liquid crystaldisplay device, on the top of the rear substrate. The active displayarea is thus defined as the volume of liquid crystal sandwiched betweenthe front polariser film and the rear polariser film or between thecircular polariser film and the metal reflector.

Denoted as a whole by the general reference numeral 1, the wristwatchcase shown only partially in a sectional view in FIG. 1 comprises amiddle part 2. This middle part 2 delimits an opening 4 that is, forexample, circular, and closed in a perfectly sealed manner by a crystal6. This crystal 6 comprises a top surface 8 directed towards the userand a bottom surface 10, opposite the top surface 8, directed towardsthe interior of the wristwatch case 1. An electro-optic display device,in this instance a liquid crystal display device 12, comprises atransparent front substrate 14 attached by any suitable means to thebottom surface 10 of the crystal 6. This front substrate 14 extendsparallel to and remotely from a rear substrate 16 that is alsotransparent. The front substrate 14 and the rear substrate 16 are joinedto one another by means of a sealing frame 18 which delimits a sealedenclosure 20 for confining a liquid crystal 22. The liquid crystaldisplay device 12 is, for example, rigidly connected by lamination bymeans of an optical clear adhesive (OCA) to the bottom surface 10 of thecrystal 6. The optical clear adhesive has the advantage of preventingparasitic optical reflection issues at the interface between the crystal6 and the liquid crystal display device 12. Electrodes 24 made of anelectrically-conductive, transparent material such as indium-tin oxide(ITO) are structured on a bottom face 26 of the front substrate 14 ofthe liquid crystal display device 12, whereas auxiliary electrodes 28,also made of an electrically-conductive, transparent material, arestructured on a top face 30 of the rear substrate 16. It should be notedthat, in the case of a liquid crystal display device of the reflectivetype, the auxiliary electrodes can be made of an electrically-conductivematerial having a mirror appearance. The electrodes 24 and the auxiliaryelectrodes 28 are arranged on either side of the layer of liquid crystal22. The application of a suitable electric voltage between a givenelectrode and a given auxiliary electrode modifies the opticalproperties of the liquid crystal 22 at the crosspoint between theelectrode and the auxiliary electrode considered.

The dimensions of the front substrate 14 of the liquid crystal displaydevice 12 are less than those of the crystal 6. The dimensions of therear substrate 16 are greater than those of the front substrate 14 butalso smaller than those of the crystal 6. It must be remembered that theelectrodes 24 and the auxiliary electrodes 28 must be connected to anexternal electronic power and control device 31. For this purpose, therear substrate 16 is designed such that it is larger than the frontsubstrate 14 and this additional surface area is used to extend, viafirst electrically-conductive tracks 32 made of anelectrically-conductive, transparent material such as indium-tin oxide(ITO), the auxiliary electrodes 28 supported by the rear substrate 16outside of the sealing frame 18 of the liquid crystal display device 22.

Similarly, the electrodes 24 supported by the front substrate 14 aretransferred to the rear substrate 16, for example by means ofelectrically-conductive balls and dispersed in the body of the sealingframe 18. These electrically-conductive balls place the electrodes 24 incontact with second conductive tracks 34 which run along the rearsubstrate 16 and allow these electrodes 24 to be extended outside of thesealed enclosure delimited by the sealing wall 18. Thanks to a flexibleprinted circuit (FPC) 36, the conductive tracks 32, 34 can be connected,and as a result, the electrodes 24 and the auxiliary electrodes 28 ofthe liquid crystal display device 12 can be connected to the externalelectronic power and control device 31 arranged on a printed circuitboard 37.

As stated hereinabove, the active display area 38 of the liquid crystaldisplay device 12 is defined by the volume of the liquid crystal 22confined inside the perimeter of the sealing frame 18 and which iscomprised between an upper polariser 39 and a lower polariser 41. Thesepolarisers 39, 41 can be crossed, i.e. the polarisation directionsthereof form a right angle, or parallel, i.e. the polarisationdirections thereof extend parallel to one another. According to theinvention, and as shown in FIG. 1 accompanying this patent application,the scope of this active display area 38 is less than the surface areaof the crystal 6. As a result, even when the liquid crystal displaydevice 12 is activated and is displaying information, a transparent area40 devoid of any displayed information remains between the activedisplay area 38 thereof and the edges of the opening 4 delimited by themiddle part 2 of the wristwatch, through which transparent area a seconddevice 42 for displaying information can be viewed, arranged beneath theliquid crystal display device 12. This second device 42 for displayinginformation can be of any kind: it can simply be a decorative pattern;it can also be a second electro-optic display device. According to aspecial embodiment of the invention shown in FIG. 1, the second displaydevice 42 arranged beneath the liquid crystal display device 12 isformed by a dial 44 above which first and second hands 46 and 48 move.Thanks to the invention, a hybrid watch is thus obtained, provided witha “screen”-type display and an analogue display, the appearance thereofbeing original and innovative.

The first hand 46 is supported by a first pipe 50, and the second hand48 is supported by a second pipe 52 arranged concentrically inside thefirst pipe 50. A hollow tube 54 is arranged inside the second pipe 52.This hollow tube 54 is intended to allow for the passage of the flexibleprinted circuit 36 which connects the conductive tracks 32, 34 and, as aresult, the electrodes 24 and the auxiliary electrodes 28 of the liquidcrystal display device 12, to the external electronic power and controldevice 31 arranged on the printed circuit board 37 which isadvantageously disposed beneath the second display device 42. Thepresence of the hollow tube 54 in which the flexible printed circuit 36is passed prevents this flexible printed circuit 36 from hindering therotation of the first and second hands 46, 48 and cannot be perceivedthrough the transparent area 40.

According to the invention, the crystal 6 is provided with an opaqueframe 56 which is made remotely from the edges of the opening 4 andwhich defines the effective surface through which the informationdisplayed by the liquid crystal display device 12 is discernible to theuser. The opaque frame 56 covers the liquid crystal display device 12 atthe periphery thereof so as to conceal the electrical connectionelements, in particular the flexible printed circuit 36, as well as thesealing frame 18 and the edges of the upper polariser 39 and lowerpolariser 41. The second display device 42 thus remains partiallyvisible through the transparent area 40 which is externally bordered bythe edges of the middle part 2 and internally bordered by the opaqueframe 56. The term “opaque frame” is understood to mean a frame whichdoes not allow light to pass and thus which fully conceals theelectrical connection elements of the liquid crystal display device 12from the user's view. For the purposes of illustration only, the opaqueframe 56 can be a coat of paint deposited by pad-printing orscreen-printing. Another possibility involves machining a groove in thecrystal 6, the geometry of which groove corresponds to the desiredgeometry of the opaque frame 56, and filling this groove with an enameldeposit. The opaque frame 56 can also be made by means of a thin metallayer or laminated film on the crystal 6.

In the remainder of this document, identical elements to those describedwith reference to FIG. 1 will be denoted using the same referencenumerals.

In FIG. 2, the conductive tracks 32, 34 and, as a result, the electrodes24 and the auxiliary electrodes 28 of the liquid crystal display device12, are connected to the external electronic power and control device 31which is arranged on a printed circuit board 58 disposed beneath thedial 44 thanks to a first flexible printed circuit 36 which extendsbetween the liquid crystal display device 12 and a transparent printedcircuit board 59 disposed beneath the liquid crystal display device 12and on which transparent conductive tracks are structured, for examplemade of indium-tin oxide (or ITO), whereas a second flexible printedcircuit 60 connects the transparent printed circuit board 59 to theprinted circuit board 58 on which the external electronic power andcontrol device 31 is arranged. It should be understood that the presenceof the opaque frame 56, of the active display area 38 of the liquidcrystal display device 12 and of the dial 44 is used to conceal from theuser's view the flexible printed circuit 36, the different components ofthe external electronic power and control device 31 and more generallyall electrical connection elements. The second display device 42 which,in the example shown in a non-limiting manner, comprises a dial 44 abovewhich first and second hands 46 and 48 move, is arranged beneath theprinted circuit board 58 such that it is partially visible through thetransparent area 40.

In FIG. 3, transparent conductive tracks 60 are structured on the bottomsurface 10 of the crystal 6. According to an alternative embodiment, thetransparent conductive tracks 60 are structured on a flexible film whichis laminated against the inner surface 10 of the crystal 6. On the otherhand, the description above shows that the electrodes 24 supported bythe front substrate 14 of the liquid crystal display device 12 aretransferred to the rear substrate 16 of the same liquid crystal displaydevice 12. Using a first flexible printed circuit 36 cleverly concealedby the opaque frame 56 and connected to the conductive tracks 32, 34supported by the top face 30 of the rear substrate 16 of the liquidcrystal display device 12, the electrodes 24 and the auxiliaryelectrodes 28 are connected to the transparent conductive tracks 60.Then, by means of a second flexible printed circuit 62 attached to thebottom surface 10 of the crystal 6 and concealed by the middle part 2,the transparent conductive tracks 60 are connected to the externalelectronic power and control device 31 of the liquid crystal displaydevice 12.

In FIG. 4, a first flexible printed circuit 36 connected to theconductive tracks 32, 34 supported by the top face 30 of the rearsubstrate 16 of the liquid crystal display device 12 allows theelectrodes 24 and the auxiliary electrodes 28 to be connected to thetransparent conductive tracks 60 structured on the bottom surface 10 ofthe crystal 6 via a second flexible printed circuit 62 withinterposition of an electrical connector 64 which acts to facilitateassembly operations between the flexible printed circuits 36 and 60.Then, by means of a third flexible printed circuit 66 attached to thebottom surface 10 of the crystal 6 and concealed by the middle part 2,the transparent conductive tracks 60 are connected to the externalelectronic power and control device 31 of the liquid crystal displaydevice 12. It should be noted that the flexible printed circuits 36 and62 in addition to the electrical connector 64 are cleverly concealed bythe opaque frame 56 and the liquid crystal display device 12.

In FIG. 5, a flexible connector 68 formed by an alternation ofelectrically-conductive sheets and of insulating elastomer sheets, inparticular known under the trade name zebra® connector, is disposedbetween the rear substrate 16 and the crystal 6. Other embodiments ofthe flexible connector 68 are also available, such as a silicon matrixin which metal wires are embedded, all of which are oriented in the samedirection. Cleverly concealed by the opaque frame 56, this flexibleconnector 68 allows the conductive tracks 32, 34 supported by the topface 30 of the rear substrate 16 of the liquid crystal display device12, and thus the electrodes 24 and the auxiliary electrodes 28, to beconnected to the transparent conductive tracks 60 structured on thebottom surface 10 of the crystal 6. Subsequently, a flexible printedcircuit 36 attached to the bottom surface 10 of the crystal 6 andconcealed by the middle part 2 allows the liquid crystal display device12 to be connected to the external electronic power and control device31 thereof.

In FIG. 6, the liquid crystal display device 12 is attached to thebottom surface 10 of the crystal 6 by the front substrate 14 thereof,which is designed such that it is larger than the rear substrate 16,this additional surface area being used to extend, via firstelectrically-conductive tracks 32, the electrodes 24 supported by thefront substrate 14 outside of the sealing wall 18. Similarly, theauxiliary electrodes 28 supported by the rear substrate 16 aretransferred to the front substrate 14, for example by means ofelectrically-conductive balls and dispersed in the body of the sealingframe 18. These electrically-conductive balls place the auxiliaryelectrodes 28 in contact with second conductive tracks 34 which runalong the front substrate 14 and allow these electrodes 24 to beextended outside of the sealed enclosure delimited by the sealing wall18. This allows, for the mounted assembly formed by the liquid crystaldisplay device 12 and the crystal 6, the conductive tracks 32, 34supported by the front substrate 14 of the liquid crystal display device12, and thus the electrodes 24 and the auxiliary electrodes 28, to beconnected, via a wire-based connection method known as wire bonding, tothe transparent conductive tracks 60 structured on the bottom surface 10of the crystal 6. The connecting wires 70 are cleverly concealed by theopaque frame 56. The connecting wires 70 can be replaced by a flexibleprinted circuit. Finally, a flexible printed circuit 36 attached to thebottom surface 10 of the crystal 6 and concealed by the middle part 2allows the liquid crystal display device 12 to be connected to theexternal electronic power and control device 31 thereof.

It is evident that this invention is not limited to the embodimentsdescribed above and that various simple alternatives and modificationscan be considered by one of ordinary skill in the art without departingfrom the scope of the invention as defined by the accompanying claims.In particular, the present invention can be applied to an organic lightemitting diode (OLED) display device as shown in FIG. 7. Denoted as awhole by the general reference numeral 72, this OLED display devicecomprises a transparent substrate 74 that acts as a support for a stackof organic layers 76 sandwiched between an anode 78 and a cathode 80.The set of layers of the OLED display device 72 is protected fromhumidity by a cover 82 which defines a sealed enclosure wherein ahumidity-absorbing device 84 is arranged. Alternatively, the set oflayers of the OLED display device 72 can be protected by the depositionof thin films. These thin films can be deposited by atomic layerdeposition (ALD). The OLED display device is attached to the bottomsurface 10 of the crystal 6 by the transparent substrate 74 thereof.Conductive tracks 86 structured on the bottom face 88 of the transparentsubstrate 74 extend outside of the sealed enclosure delimited by thecover 82. This allows, for the mounted assembly formed by the OLEDdisplay device 72 and the crystal 6, the conductive tracks 86 supportedby the transparent substrate 74 of the OLED display device 72, to beconnected, via a wire-based connection method known as wire bonding, tothe transparent conductive tracks 60 structured on the bottom surface 10of the crystal 6. The connecting wires 90 are cleverly concealed by theopaque frame 56. The connecting wires 90 can be replaced by a flexibleprinted circuit. Finally, a flexible printed circuit 92 attached to thebottom surface 10 of the crystal 6 and concealed by the middle part 2allows the OLED display device 72 to be connected to the externalelectronic power and control device 94 thereof arranged on a printedcircuit board 96. The active display area 98 of the OLED display device72 is defined by the overlap area between the anode 78 and the cathode80. This active display area 98 has a metallic appearance in the absenceof a circular polariser, and will appear dark if such a circularpolariser is used. In accordance with the invention, an opaque frame 100is provided on the top surface 8 of the crystal 6, remotely from theedges of the opening 4, and covers the active display area 98 of theOLED display device 72 at the periphery thereof in order to delimit theeffective surface through which the information displayed by the OLEDdisplay device 72 is discernible to the user. A transparent area 102devoid of any displayed information thus remains between the edges ofthe opening 4 and the outer contour of the opaque frame 100, throughwhich transparent area a second display device 42 can be viewed, such asa dial 44 above which first and second hands 46, 48 move, arrangedbeneath the OLED display device 72. In the example shown in FIG. 7, theOLED display device 72 is of the bottom emission type, i.e. lightemerges from the OLED display device 72 through the transparentsubstrate 74. In the case where the OLED display device 72 is of the topemission type, i.e. the case where light emerges from the OLED displaydevice 72 on the opposite side to the transparent substrate 74, the OLEDdisplay device 72 can be designed to be attached to the bottom surface10 of the crystal 6 via the cover 82 thereof. In the case where the OLEDdisplay device 72 is protected from humidity by the deposition of thinfilms over the entirety of the layers thereof, the OLED display device72 is attached to the bottom surface 10 of the crystal 6 via the thinfilms.

NOMENCLATURE

-   1. Wristwatch case-   2. Middle part-   4. Opening-   6. Crystal-   8. Top surface-   10. Bottom surface-   12. Liquid crystal display device-   14. Front substrate-   16. Rear substrate-   18. Sealing frame-   20. Sealed enclosure-   22. Liquid crystal-   24. Electrodes-   26. Bottom face-   28. Auxiliary electrodes-   30. Top face-   31. External electronic power and control device-   32. First electrically-conductive tracks-   34. Second electrically-conductive tracks-   36. Flexible printed circuit-   37. Printed circuit board-   38. Active display area-   39. Upper polariser-   40. Transparent area-   41. Lower polariser-   42. Second display device-   44. Dial-   46, 48. First and second hands-   50. First pipe-   52. Second pipe-   54. Hollow tube-   56. Opaque frame-   58. Printed circuit board-   59. Transparent printed circuit board-   60. Transparent conductive tracks-   62. Second flexible printed circuit-   64. Electrical connector-   66. Third flexible printed circuit-   68. Flexible connector-   70. Connecting wires-   72. OLED display device-   74. Transparent substrate-   76. Stack of organic layers-   78. Anode-   80. Cathode-   82. Cover-   84. Humidity absorbing device-   86. Conductive tracks-   88. Bottom face-   90. Connecting wires-   92. Flexible printed circuit-   94. External electronic power and control device-   96. Printed circuit board-   98. Active display area-   100. Opaque frame-   102. Transparent area

1. An object comprising: an electro-optic display device externally delimited by a contour and which is provided with an optically active element, whose optical properties can be modified by applying an electric voltage or current between at least one electrode and one corresponding auxiliary electrode, between which the optically active element is disposed, a middle part which delimits an opening closed by a crystal, the crystal comprising a top surface and a bottom surface beneath which the electro-optic display device is arranged, an external electronic power and control device in addition to elements for the electrical connection of the electro-optic display device to the external electronic power and control device, the crystal being provided with an opaque frame which is made remotely from the edges of the opening and which covers the contour of the electro-optic display device so as to conceal the electrical connection elements, the electro-optic display device defining an active display area which is delimited by the opaque frame, such that, even when the electro-optic display device is activated and displays information, a transparent area remains between the opaque frame and the edges of the opening, wherein the active display area includes a polarizer, and the polarizer does not extend into the transparent area such that an area beneath the transparent area is visible when the electro-optic display device is activated and displays the information.
 2. The object according to claim 1, further comprising a second display device arranged beneath the electro-optic display device and at least partially visible through the transparent area.
 3. The object according to claim 2, wherein the second display device comprises a dial above which first and second hands move.
 4. The object according to claim 3, wherein the electro-optic display device is a liquid crystal display device.
 5. The object according to claim 4, wherein the first hand is supported by a first pipe, and the second hand is supported by a second pipe arranged concentrically inside the first pipe, the liquid crystal display device being connected to the external electronic power and control device via a flexible printed circuit which is passed in a hollow tube arranged inside the second pipe.
 6. The object according to claim 4, wherein the liquid crystal display device is connected to the external electronic power and control device which is arranged on a printed circuit board disposed beneath the dial thanks to a first flexible printed circuit which extends between the liquid crystal display device and a transparent printed circuit board disposed beneath the liquid crystal display device, a second flexible printed circuit connecting the transparent printed circuit board to the printed circuit board on which the external electronic power and control device is arranged.
 7. The object according to claim 4, wherein transparent conductive tracks are structured on the bottom surface of the crystal, the liquid crystal display device being connected to these transparent conductive tracks with a first flexible printed circuit, the transparent conductive tracks being themselves connected with a second flexible printed circuit to the external electronic power and control device of the liquid crystal display device, which is concealed by the middle part, the second display device being disposed beneath the liquid crystal display device.
 8. The object according to claim 4, wherein transparent conductive tracks are structured on the bottom surface of the crystal, the liquid crystal display device being connected to these transparent conductive tracks with a first flexible printed circuit and of a second flexible printed circuit connected to the first flexible printed circuit with an electrical connector, a third flexible printed circuit connecting the transparent conductive tracks to the external electronic power and control device of the liquid crystal display device, the second display device being disposed beneath the liquid crystal display device.
 9. The object according to claim 4, wherein the liquid crystal display device is connected to transparent conductive tracks structured on the bottom surface of the crystal with a flexible connector formed by an alternation of electrically-conductive sheets and of insulating elastomer sheets, a flexible printed circuit allowing the transparent conductive tracks to be connected to an external electronic power and control device of the liquid crystal display device, the second display device being disposed beneath the liquid crystal display device.
 10. The object according to claim 3, wherein the electro-optic display device is an OLED display device.
 11. The object according to claim 10, wherein the OLED display device is of the bottom emission type and comprises a transparent substrate via which it is attached to the bottom surface of the crystal, this transparent substrate acting as a support for a stack of organic layers protected from humidity by a cover or by thin films that define a sealed enclosure, conductive tracks structured on a bottom face of the transparent substrate extending outside of the sealed enclosure and being connected by connecting wires to transparent conductive tracks structured on the bottom surface of the crystal which are themselves connected, via a flexible printed circuit, to an external electronic power and control device of the OLED display device.
 12. The object according to claim 10, wherein the OLED display device is of the top emission type and comprises a transparent substrate acting as a support for a stack of organic layers protected from humidity by a cover or by thin films that define a sealed enclosure, the OLED display device being attached to the bottom surface of the crystal via the cover thereof or via the thin films thereof.
 13. The object according to claim 1, wherein the object is a timepiece or smartphone. 